原来2.0里实现数据绑定控件这么简单!

  1using System;
  2using System.Collections.Generic;
  3using System.ComponentModel;
  4using System.Text;
  5using System.Web;
  6using System.Web.UI;
  7using System.Web.UI.WebControls;
  8
  9
 10namespace WYN.WebControls
 11{
 12
 13    [ToolboxData("<{0}:FilterTextBox runat=server></{0}:FilterTextBox>")]
 14    public class FilterTextBox : DataBoundControl 
 15    {
 16        private ListItemCollection listSource = null;
 17        protected ListItemCollection ListSource
 18        { 
 19            get{
 20
 21                if (listSource == null)
 22                    listSource = new ListItemCollection();
 23
 24                return listSource;
 25            }
 26       
 27        }
 28
 29        private int selectedIndex = 0;
 30        public  int SelectedIndex
 31        {
 32            get
 33            {
 34
 35                return selectedIndex;
 36            }
 37            set
 38            {
 39                selectedIndex = value;
 40
 41                if (selectedIndex < 0 || selectedIndex > ListSource.Count)
 42                {
 43                    selectedIndex = 0;
 44                }
 45
 46                if (listSource.Count != 0)
 47                {
 48                    listSource[selectedIndex].Selected = true;
 49                }
 50            }
 51        }
 52
 53        public string DataTextField
 54        {
 55            get
 56            {
 57                object o = ViewState["DataTextField"];
 58                return ((o == null) ? string.Empty : (string)o);
 59            }
 60            set
 61            {
 62                ViewState["DataTextField"] = value;
 63                if (Initialized)
 64                {
 65                    OnDataPropertyChanged();
 66                }
 67            }
 68        }
 69
 70        public string DataValueField
 71        {
 72            get
 73            {
 74                object o = ViewState["DataValueField"];
 75                return ((o == null) ? string.Empty : (string)o);
 76            }
 77            set
 78            {
 79                ViewState["DataValueField"] = value;
 80                if (Initialized)
 81                {
 82                    OnDataPropertyChanged();
 83                }
 84            }
 85        }
 86
 87
 88        protected override void PerformSelect()
 89        {
 90
 91            // Call OnDataBinding here if bound to a data source using the
 92            // DataSource property (instead of a DataSourceID), because the
 93            // databinding statement is evaluated before the call to GetData.       
 94            if (!IsBoundUsingDataSourceID)
 95            {
 96                OnDataBinding(EventArgs.Empty);
 97            }
 98
 99            // The GetData method retrieves the DataSourceView object from  
100            // the IDataSource associated with the data-bound control.            
101            GetData().Select(CreateDataSourceSelectArguments(),
102                OnDataSourceViewSelectCallback);
103
104            // The PerformDataBinding method has completed.
105            RequiresDataBinding = false;
106            MarkAsDataBound();
107
108            // Raise the DataBound event.
109            OnDataBound(EventArgs.Empty);
110        }
111        private void OnDataSourceViewSelectCallback(System.Collections.IEnumerable retrievedData)
112        {
113
114            // Call OnDataBinding only if it has not already been 
115            // called in the PerformSelect method.
116            if (IsBoundUsingDataSourceID)
117            {
118                OnDataBinding(EventArgs.Empty);
119            }
120            // The PerformDataBinding method binds the data in the  
121            // retrievedData collection to elements of the data-bound control.
122            PerformDataBinding(retrievedData);
123        }
124
125
126        protected override void PerformDataBinding(System.Collections.IEnumerable retrievedData)
127        {
128            base.PerformDataBinding(retrievedData);
129
130            // If the data is retrieved from an IDataSource as an 
131            // IEnumerable collection, attempt to bind its values to a 
132            // set of TextBox controls.
133            if (retrievedData != null)
134            {
135
136                foreach (object dataItem in retrievedData)
137                {
138
139                    ListItem item = new ListItem();
140
141
142                    if (!String.IsNullOrEmpty(DataTextField))
143                    {
144                        item.Text = DataBinder.GetPropertyValue(dataItem,
145                            DataTextField, null); //以后要加上DataFormat
146
147                        item.Value = DataBinder.GetPropertyValue(dataItem,
148                            DataValueField, null);
149                    }
150                    else
151                    {
152                        PropertyDescriptorCollection props =
153                            TypeDescriptor.GetProperties(dataItem);
154
155                        // Set the "default" value of the TextBox.
156                        item.Text = "";
157                        item.Value = "";
158
159                        // Set the true data-bound value of the TextBox,
160                        // if possible.
161                        if (props.Count >= 1)
162                        {
163                            if (null != props[0].GetValue(dataItem))
164                            {
165                                item.Text = props[0].GetValue(dataItem).ToString();
166                                item.Value = props[0].GetValue(dataItem).ToString();
167                            }
168                        }
169                    }
170
171                    ListSource.Add(item);
172                }
173            }
174        }
175
176        public override void RenderBeginTag(HtmlTextWriter writer)
177        {
178            writer.WriteBeginTag("div>");
179        }
180
181        protected override void RenderContents(HtmlTextWriter output)
182        {
183            // Make sure the control is declared in a form tag 
184            // with runat=server.
185            if (Page != null)
186            {
187                Page.VerifyRenderingInServerForm(this);
188            }
189            
190
191            //生成输入文本框的Html字符串,呈现在页面
192            String inputTextBox = prepareInputBox();
193            output.Write(inputTextBox);
194
195            output.Write("<BR>");
196
197            //生成备选框的Html字符串,呈现在页面
198            String listBox = prepareListBox();
199            output.Write(listBox);  
200
201        }
202
203
204        public override void RenderEndTag(HtmlTextWriter writer)
205        {
206            writer.WriteEndTag("div");
207        }
208
209        Private#region Private
210        /**//// <summary>
211        /// 生成输入文本框的Html字符串
212        /// </summary>
213        /// <returns></returns>
214        private String prepareInputBox()
215        {
216            String id = this.ClientID + "_inputBox";
217            String txtHtmlString = String.Format("<input name=\"{0}\" type=\"text\" id=\"{0}\" />", id);
218
219            return txtHtmlString;
220        }
221        /**//// <summary>
222        /// 生成备选框的Html字符串
223        /// </summary>
224        /// <returns></returns>
225        private String prepareListBox()
226        {
227            String id = this.ClientID + "_listBox";
228            StringBuilder sbHtmlString = new StringBuilder(String.Format("<select name=\"{0}\" id=\"{0}\">",id));
229            sbHtmlString.Append("\r\n");
230            foreach (ListItem item in ListSource)
231            {
232
233                sbHtmlString.Append("<option value=\"");
234                sbHtmlString.Append(item.Value);
235
236                if (item.Selected)
237                    sbHtmlString.Append("Selected");
238
239                sbHtmlString.Append("\">");
240                sbHtmlString.Append(item.Text);
241                sbHtmlString.Append("</option>");
242                sbHtmlString.Append("\r\n");
243            }
244            sbHtmlString.Append("</select>");
245            return sbHtmlString.ToString();
246            
247        }
248        #endregion
249    }
250}
251